At the present time, in countries around the world, digitalization is being promoted in broadcast systems using a ground wave, a satellite wave, a cable, and the like. Digital signals are superior to analog signals in stability, and have a high data compression rate. Thus, in digital broadcasting, more channels can be ensured within a given bandwidth compared to broadcasting with analog signals. In addition, in digital broadcasting, a data broadcast can also be transmitted, which makes it possible to realize a hybrid broadcast service in combination with another service.
For example, with regard to digital broadcasting utilizing the ISDB (Integrated Services Digital Broadcasting) system started in Japan in 2000, data broadcasting is one of its features. In this system, in addition to video and audio data (AV data) composing the main body of a broadcast program, digital transmission data associated with the broadcast program (hereinafter referred to as “data for data broadcast or data-broadcast data”) is delivered in parallel with the AV data by a broadcaster or the like. To be more specific, the broadcast signal is delivered in the form of a transport stream composed by multiplexing AV data compressed by a certain compression method such as MPEG (Moving Picture Expert Group) 2 and data for data broadcast coded in a coding method such as BML (Broadcast Markup Language). BML is based on XML (eXtensible Markup Language) and includes functions such as a function for specifying a location of multimedia data, a script execution function by ECMA script which is a standard description of Java (registered trademark) script, and a function for operating XML by the DOM (Document Object Model).
A data broadcast for TVs, for example, is displayed when a user viewing a television program (hereinafter referred to as “broadcast content”) manipulates a “d” (data linkage) button provided on a remote controller. Specifically, when the “d” button is manipulated at a time where the broadcast content is being fully displayed on the TV screen, a browser for data broadcasting which interprets the data for data broadcasting written in the BML format is activated, and the state of the screen changes to a data broadcast display.
The data for data broadcast, for example, includes media data such as a still picture, moving picture, sound, figure, and character, and a data broadcast application which merges these pieces of data and controls the expression form and operation thereof. The user (viewer of the digital broadcast), for example, can instruct an operation of each media data piece on the data broadcast display screen by using a cursor key, a decision key, a color button, or number buttons (number keypad) on the remote controller. Utilities such as broadcasters can realize a data broadcast service associated with the main broadcast program by using the data broadcast application.
The Java (registered trademark) technique, for example, can be applied to the data broadcast application. In a case applying the Java technique, the data broadcast application is composed of class files which are byte codes operated on a Java (registered trademark) virtual machine. The Java virtual machine within a receiver (e.g., a television set) runs received class files, thereby providing the data broadcast service to the viewer. There are plural class files necessary for executing one Java (registered trademark) data broadcast service. Thus, the Java (registered trademark) data broadcast service cannot be executed until all of the class files are obtained. It is also possible to accumulate in the receiver class files that were used when a certain Java (registered trademark) data broadcast service was executed once, and utilize the class files for a similar Java (registered trademark) data broadcast service thereafter. For example, there is proposed a program file acquiring apparatus which acquires lacked one(s) of essential program files essential to execute the broadcast service specified by the user through a selected acquisition path (for example, refer to PTL 1).
On the other hand, along with the spread of broadband communication networks, it has become possible to transmit large-capacity data of a moving picture or the like through the Internet. For example, an information processor is proposed which can download and accumulate content such as a movie through the Internet (hereinafter referred to as “network content”), and can reproduce the network content at any timing (for example, refer to PTL 2). In addition, there is proposed a receiver which changes a display state of broadcast content and a display state of network content in a seamless manner (for example, refer to PTL 3).
According to the receiver of the latter, a shared browser which can display both of the data broadcast display and the pseudo data broadcast display (i.e., capable of interpreting both BML and HTML) is run in advance. The shared browser controls displaying/non-displaying, thereby enabling mutual and direct shifting between the data broadcast display in a broadcast content mode and the pseudo data broadcast display in a network content mode in a seamless manner.
However, although this receiver executes a process for merging the broadcast content and the network content, the receiver does not differ from a technology in the related art in that it displays the network content by interpreting HTML. That is to say, this receiver does not interpret BML, that is, does not display the network content as a data broadcast service. In other words, a broadcaster or the like cannot provide by data broadcasting a hybrid broadcast service in which broadcast content and network content are combined.